(a) Field of the Invention
The present invention relates to a non-magnetic mono-component toner composition, and more particularly to a non-magnetic mono-component toner composition which has superior transfer efficiency and charging properties, and thus can obtain stable images, does not show deteriorated image density, and does not generate background contamination of non-image areas and off-set due to deterioration of fixing properties, even if copying or printing is conducted therewith for a long time use.
(b) Description of the Related Art
Generally, according to conventional electrophotography methods, an electrostatic latent image forms on the surface of a photosensitive member using photoconductive materials, the latent image is developed using a toner, and the toner image is transferred to a recording medium such as paper to obtain a copy fixed by heat or pressure, as disclosed in U.S. Pat. No. 2,297,691, Japanese Laid-Open Patent Publication No. 42-23910, Japanese Laid-Open Patent Publication No. 43-24748, etc.
Additionally, various development methods for developing electrostatic latent images using a toner are also known. For example, U.S. Pat. No. 2,874,063 discloses a magnetic brush development method, U.S. Pat. No. 2,618,552 discloses a cascade development method, Japanese Laid-Open Patent Publication No. 41-9475 discloses a development method using a mono-component insulating toner, and U.S. Pat. No. 3,909,258 discloses a development method using a mono-component conductive toner, and among the above, the dual-component magnetic brush development method and the mono-component insulating toner development method are predominantly used.
However, the electrophotography development method wherein a photosensitive member is uniformly charged, an electrostatic latent image forms by light exposure or laser beam, and a toner is supplied to the electrostatic latent image to form a visual image, has a problem in that ozone is generated from a charging apparatus. Particularly, taking environmental aspects into consideration, an organic photosensitive member that is most widely used generally has a negative charge property, and thus prevention of ozone generation during the charging process is difficult.
In order to reduce ozone, a contact charging method has been suggested wherein a conductive member such as a conductive brush, a conductive elastic member roller, etc. is contacted with a photosensitive member and voltage is applied. However, such contact charging method involves a problem in terms of contamination of the conductive members. Since the conductive member is in contact with a photosensitive member, a toner, external additive for a toner, etc. that are attached to the photosensitive member are in turn attached to the conductive member to generate an irregular charging on the surface of the photosensitive member.
In order to solve the above problems, an organic photosensitive member having a positive charge property has been developed. If a positive charge is used, even if a corona charging method is used, ozone generation can be reduced to approximately 1/10 compared to a negative charge.
Meanwhile, a non-magnetic mono-component toner used in the positive charging development method requires high transfer efficiency and high chargeability compared to the negative charging development method. For this, an external additive is attached to a toner particle. However, in the case a toner to which one kind of external additive is attached is used for the non-magnetic mono-component development method, since there is friction between the toner particle and a doctor blade or a developing roller, the external additive attached to the toner particle surface is embedded in the toner particle, and thus the flowability-increasing effect of the external additive deteriorates, and transfer efficiency and charging properties are not sufficient, thereby deteriorating the image after printing and the long term stability of the image.
In order to solve the above problems, a method has been suggested wherein a toner with a positive charge property is developed onto a surface of a positively charged organic photosensitive member, the toner that is developed with high transfer efficiency is transferred to a reporting medium such as paper, and fine powder of an organic compound containing fluorine is used in addition to a single external additive of hydrophobic silica in order to reduce image background contamination. However, this method involves a problem in that off-set is generated in the fixing process.
Accordingly, there are increasing needs for a non-magnetic mono-component toner that has superior transfer efficiency and charging properties, and does not generate background contamination of non-image areas and off-set due to deterioration of fixing properties.